ABSTRACT
Beyond the orbit of Neptune lie the remnants of a formerly substantial planetesimal population. The present-day orbital properties of these trans-Neptunian objects (TNOs) bear the marks of an early dynamical upheaval in the outer solar system that may have even ejected along-lost ice giant sibling to Neptune and Uranus. However, decoding the evolutionary record etched in the orbital properties of TNOs requires rewinding billions of years of complex dynamical evolution. I will describe how analytical insights into this evolution can be obtained using a simple mapping approach. Then I will turn my attention to exoplanetary systems which, based on hints of a large population of free-floating planets from ground-based gravitational microlensing surveys, appear to frequently experience similar dynamical upheavals during their early evolution. But the details of such planet-liberating dynamical instabilities have previously not received much attention. I will show that in systems that lack Jupiter-mass giant planets, instabilities lead to prolonged bouts of planet-planet scattering during which multiple planets are thrown onto loosely-bound, highly eccentric orbits. These long-lived scattering phases can last billions of years and, since giant planets are known to be relatively rare, this implies that a substantial fraction of apparently free-floating planets detected by microlensing surveys are actually loosely-bound planets that only appear to be free-floating. These results have important implications for how we interpret the thousands of microlensing planet discoveries, both bound and free-floating, expected from NASA's upcoming Roman mission.
BIO
For more information about the PDS workshop, please visit:
https://i.astro.tsinghua.edu.cn/~wzhu/PDS2024
